☽ Tarabalam Calculator: the Nine Taras of Your Next 30 Days

Give your birth nakshatra, your Moon sign or your birth date, and where you are. Each row is one Vedic day, sunrise to sunrise, with the Moon's nakshatra and sign, the minute it changes, and the sum behind each answer.

Tarabalam, the strength of the star, is the quickest personal test in Vedic muhurta, the craft of choosing a day. It needs one fact about you: the nakshatra the Moon was in when you were born, your Janma nakshatra. Every day the Moon is somewhere among the 27 nakshatras. Count from yours to the day's, and the count says whether the Moon that day stands as a friend or an obstacle to your own.

The method is a count and a remainder. Call your birth nakshatra 1, count forward to the day's nakshatra (counting both ends), divide by 9 and keep the remainder; a remainder of 0 is read as 9. The remainder is the tara. Twenty-seven nakshatras and nine taras means each tara comes round three times, so the first, tenth and nineteenth nakshatras from yours are all Janma tara, and about one day in nine falls in each.

Reading: the favourable taras are 2, 4, 6, 8 and 9 (Sampat, Kshema, Sadhana, Mitra, Parama Mitra); the unfavourable are 1, 3, 5 and 7 (Janma, Vipat, Pratyak, Naidhana). That is the muhurta reading printed in common almanacs and attributed to the classical muhurta compilations (the Muhurta Chintamani and Muhurta Martanda tradition). Umbriel has followed the version in current almanacs and has not checked it against a particular verse; teachers differ on details, most often on Janma, which some treat as neutral and others as a day to avoid for new beginnings.

Suppose your birth nakshatra is Punarvasu, number 7, and the Moon is in Vishakha, number 16. The count is 16 − 7 + 1 = 10. Ten divided by nine leaves 1, so the tara is 1, Janma. It is the second turn of the 27 (the tenth from your birth star, called Anujanma), and it is read as unfavourable. If the Moon were in Swati, number 15, the count would be 9, the remainder 0 counts as 9, and the tara would be Parama Mitra, the best friend.

Every day in the calendar carries its own version of that sum, behind the words "the arithmetic", written with your nakshatra and the day's.

An almanac names a day after the nakshatra at sunrise, but the Moon crosses into the next nakshatra during most days. A day that opens in Sadhana can turn into Naidhana by early afternoon. Umbriel therefore shows each stretch of the day separately, with the minute the Moon changes, and marks the stretch that is running now. The day's own tara is the one at sunrise, in the first line of the row.

Choose "I know my birth date". The Moon moves about 13° in a day, close to one nakshatra, so on most birth dates it changed nakshatra at some hour. Without a birth time Umbriel does not guess. It lists every nakshatra and sign the Moon passed through on your birth date with the times, then shows the calendar for each possibility and tells you wherever they would give different answers. With a birth time the range collapses to one, and the page warns you when the Moon sat within 0.1° of a nakshatra edge, since a few minutes' error would change it.

The Moon comes from the same engine that casts every chart on Umbriel, in the sidereal zodiac with the Lahiri ayanamsa. The calendar finds each moment the Moon crosses a nakshatra boundary (every 13°20′) or a sign boundary (every 30°) by stepping through the month two hours at a time and then halving the interval until the crossing is pinned to a fraction of a second. Sunrise is the Sun's upper edge at the horizon for the place you choose, the Vedic day's own starting line, so each day runs from one sunrise to the next. The classification is then pure counting, and the sum is printed under every answer. Nothing is sent anywhere: the page works in your browser, and the calculation engine (about 780 KB) is only fetched when you first touch the form.

Checked, not assumed. The engine's Moon was compared with NASA JPL Horizons (apparent longitude of date, the geocentre) at 80 instants spread from 1950 to 2161. For the 66 of them up to the end of 2027 the largest difference was 0.17 arcminute (0.07 on average), about twenty seconds of the Moon's travel; the engine drifts to a few arcminutes by the 2100s, so only dates in the next few decades are this exact. Against a published online panchang (Drik Panchang) on five days in five places (New Delhi, Mumbai, Chennai, Kolkata and New York, between October 2026 and March 2027) every nakshatra and Moon-sign change time agreed to within one minute, and our sunrise came 1 to 1.5 minutes earlier than theirs. Not checked: the classical verse for each convention below (see the questions), birth times from before 1970 (the zone rules come from your browser, and old daylight-saving rules are the likeliest thing to be wrong), and anything beyond 30 days ahead, which the calendar does not offer.

Tarabalam is one test among many. A classical muhurta weighs the tithi, the weekday, the yoga, the Moon's sign and more, and none of it is a forecast. Umbriel shows the arithmetic of a tradition for reflection and planning; it does not claim that a Sadhana day will go well or a Vipat day badly.